Does Soy Cause Hair Loss?

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Soy is undoubtedly one of the most nutritious foods in the world. Soy products are particularly rich in proteins. While soy’s general nutritive benefits to the human body are not in doubt, questions have been asked regarding the impact that soy and soy products have on specifically the human hair.

Some studies have gone as far as suggesting that soy actually makes some hair conditions worse. So, does soy actually cause hair loss? This article will answer your questions.

What is Soy?

Soy is a general term used to represent products that have been made from soybeans. The beans are seeds from Glycine max, a plant initially cultivated in China. From China, soybeans have since spread to other areas of the world.

The United States of America is the world’s leading producer of soybeans, though most of the produce goes towards production of soy oil and livestock feeds. Some of the well-known soy products for human consumption include soy milk, soy oil, tofu, natto, tempeh, and edemame.

Is Soy Good for Your Hair?

While the available studies on this topic do not offer us conclusive evidence, most scientific studies have revealed that soy is actually good for your hair.

The following are some of the main study results regarding soy and the health of your hair.

Soy May Prevent Androgenic Alopecia

According to one study, soy may help to slow down or prevent the progress of androgenic alopecia, commonly called male-pattern baldness.

The condition is caused by an androgen hormone called dihydrotestosterone (DHT) which is a by-product of the male sex hormone testosterone. Although the exact mechanism is unclear, DHT is said to disrupt the hair growth cycle.

The androgen causes premature miniaturization of hair follicles on the scalp. The hair follicles undergo massive shrinking such that they can no longer grow into mature hairs, leading to baldness.

Soy contains a molecule called equol that results from the digestion of proteins. According to the research, equol behaves like an anti-androgen and effectively binds and blocks the operations of DHT without affecting the work of testosterone itself.

This means that the growth of hair follicles proceeds uninterrupted hence keeping hair loss at bay.

The results of the above study are in tandem with those of a similar study carried out by US researchers from Colorado State’s College of Veterinary Medicine.

The researchers concluded that equol, the molecule resulting from the digestion of soy proteins, can prevent the development of both prostate cancer and baldness.

They found that equol “handcuffs” DHT thereby preventing it from attacking the hair follicles. The research head, Professor Robert Handa, had this to say:

“Directly binding and inactivating DHT without influencing testosterone gives equol the ability to reduce many of the harmful effects of androgens, [male hormones] without affecting the beneficial ones.”

Although this evidence suggests soy can actually help you prevent androgenic alopecia, it is imperative to take the results with some precaution as research into the topic is still inconclusive.

Soy May Alleviate Alopecia Areata (AA)

A different study shows that soy extracts can alleviate alopecia areata, a scalp condition associated with inflammation of hair follicles that leads to hair loss.

In the study, mice were fed different amounts of soy oil – 1%, 5%, and 20% of soy oil. At the end of the study, the results revealed that the mice developed some resistance to alopecia areata induced through skin grafting.

The highest resistance was exhibited by the mice that had been put on a 20% soy oil diet, suggesting that the response was largely dose-dependent. In addition, injection of isoflavone genistein (a protein inhibitor in soy) into mice actually reduced the occurrence of AA.

Soy Added to Shampoos Makes Them More Effective

It turns out that soy-based surfactants are very effective when added to commercial shampoos.

In a study published in the International Journal of Cosmetic Science, the objective was to evaluate the performance of soybean oil-based polymeric surfactant (SBPS) in model shampoo formulations.

The results revealed that a shampoo formulation containing SBPS and an additional anionic surfactant (the study used sodium lauryl sulfate) exhibited better foaming and cleaning ability compared to a shampoo containing sodium lauryl sulfate as the only surfactant.

In addition, the study showed that SBPS makes it possible to reduce the concentration of sodium lauryl sulfate in commercial shampoos without compromising performance. As such, soy-based surfactants that are in fact less expensive can help in reducing the price of hair shampoos.

Soy Can Help Keep the Scalp Hydrated

Scalp peel

Further research suggests that isoflavone geinstein, contained in soy extract, is able to stimulate the production of hyaluronic acid (HA).

This is a carbohydrate found in most parts of the body, including the dermis and the epidermis. HA is present in the scalp tissue, where it holds water and helps form a gelatinous fluid that keeps the deep tissues in the scalp nourished and hydrated.

Such an environment is perfect for the growth of hair follicles. It has also been suggested that HA forms a gel-like shield that protects hair follicles from DHT hence can also help prevent androgenic alopecia.

Taken together, science strongly suggests that soy is a putative treatment that can actually help prevent hair loss. Soy is also arguably less expensive than some hair loss prescription drugs and therefore can be a viable alternative without sacrificing performance.

It is important to remember that soy is very rich in proteins and can be very good for the entire human body. If the rest of the body is healthy, this means that there will be plenty of nutrients to help your hair grow.

Who Should Avoid Soy?

Although soy is considered safe for most people, some studies suggest there a few categories of people who might want to avoid it altogether. These are:

  • Breast cancer survivors. The effect of soy isoflavones on breast cancer survivors has been the subject of conflicting research results, with some studies concluding that isoflavines can cause the reproduction of cancerous cells. Although the research is inconclusive, physicians advise breast cancer survivors to avoid soy and soy-based products.
  • People who are allergic to soy. Soybean allergy is one of the most common allergies especially among babies and young children. The Food Allergen Labeling and Consumer Protection Act (FALCPA) in the United States requires that all products containing soy as an ingredient must include the word “soy” on the label. To prevent a reaction, it is important to avoid soy and all soy-based products.


Research regarding the effects of soy on hair remains inconclusive, though most studies are leaning on the positive side, suggesting that soy can help prevent hair loss and enhance healthy hair growth.

It is important to involve your doctor before deciding to include soy in your diet. Despite the positive evidence, it is also very important to have realistic expectations. Taking soy products may not guarantee you protection from hair loss.

If you are looking for a hair loss solution that offers a greater guarantee, you might have to go for a combination of proven medical treatments that are right for you.